使用WCF的MVVM WPF应用程序但缺少“模型”

I'm creating a WPF application with MVVM framework. The data is then retrieved by accessing a WCF service exposing the data based on Entity framework model. Is there anything wrong with this? It seems that the "Model" portion of MVVM seems to be missing.I'm creating a WPF application with MVVM framew